Leonardo inside out

Leonardo da Vinci, the extraordinary polymath who for many embodies the epitome of the true Renaissance man, left us some of the most remarkably naturalistic drawings of the human body. His interest in writing a book on the human body is well documented, going back at least to his early days in Milan in the late 1480s. “You should begin with the conception of man,” he wrote (Windsor, RL 19037v, 1489 and c.1508), “and describe the form of the womb, and how the child lives in it, and to what stage it resides in it and in what way it is given life and food.” The note concluded with a list of figures that had to accompany the book, including that “of a woman, to demonstrate the womb and the menstrual veins which go to the breast.”

When he later represented so eloquently the inner structure of the female body in what is known as the ‘Female Situs’ (Windsor RL 12281r, c.1507-09), he reminded himself that his arrangement should start “with the beginning of the formation of the infant in the womb, stating which part of it is composed first; and so on successively putting in its parts according to the duration of the pregnancy until birth; and learning how it is nourished partly from the eggs which hens make.”

The drawing is clearly a composite of direct observation gained from dissection and remarkably vivid visualization based on Leonardo’s reading of the anatomical literature. Yet Leonardo’s unmatched ability to give depth to the internal organs of the body distinguishes him from many of his contemporaries: his concern to demonstrate visually to his reader the secrets of the human body emerges again and again in the pages of his manuscripts. To this effect, on this very same sheet he appended the note: “Make this demonstration seen also from the side in order that knowledge may be given as to how much one part is behind another; and then make one from behind in order that knowledge of the vessels located near the spine and heart and great blood vessels may be given.” We will have to wait until Andreas Vesalius’s De humani corporis fabrica (1543) to see comparable 3D representations of the internal organs of the female body.

Leonardo’s long-lasting fascination with the themes of reproduction and generation culminated in the beautiful drawings of the fetus in the womb. While Leonardo’s interest in internal anatomy was unique among the artists of his time, this was clearly not the case for late medieval and Renaissance Italian physicians. The growing body of commentaries by the Bolognese natural philosophers and physicians Taddeo Alderotti (d. 1295), Tommaso del Garbo (d. 1370), Jacopo da Forlì (d. 1414) and especially that of the highly influential anatomist Mondino de’ Liuzzi (d. 1326), whose work Leonardo discussed in another note in the ‘Female Situs’ sheet, bear testimony to the pressing interest of these medical practitioners in the inner workings of the female body and particularly the uterus as the hidden site of generation; while the results of reproduction were in front of everybody to observe, the mechanisms were wrapped in mystery. For this reason they remained an issue of debate for generations of physicians, theologians and natural philosophers, and in Leonardo’s time there was little consensus on a wide range of questions that ranged from the role of female semen in reproduction to the process of ensoulment or the way the baby was nourished in the womb.

The famous drawing of the coition of a hemisected man and woman – clearly another example of Leonardo’s powerful tools of visualization – beautifully illustrates Leonardo’s concerns with these natural philosophical questions. In Windsor, RL 19097v, written around 1493, he penciled: “Note what the testicles have to do with coition and the sperm. And how the infant breathes and how it is nourished through the umbilicus. And why one soul governs two bodies as you see the mother desiring a food and the infant remaining marked by it.”

The question whether the fetus breathes in the womb or not was one of the most commented sections of the encyclopedic Canon of Medicine by the Persian natural philosopher and physician Avicenna (Ibn Sīnā, c. 980-1037), the staple text for the teaching of human anatomy and physiology in Italian universities. How the fetus was nourished through the umbilical cord was particularly controversial, as Galen had argued that two channels existed, one for the food and one for the urine, a claim endorsed by Mondino. Leonardo and his contemporary, the surgeon Berengario da Carpi, however, argued that there was only one channel (Windsor, RL 19101v, top right corner) and Leonardo maintained that this was both “the channel for the food, and the passage for the urine,” but that the two did not travel through it at the same time. According to Leonardo:

During a great part of the period of life of the foetus its urination is through the umbilicus. And this happens because the heel of the right [left] foot comes between the anus and the penis and shuts off the passage of all urine. Nature has provided for this by making a channel in the fundus of the bladder [urachus] through which urine goes from the bladder to the umbilicus and from the umbilical cord to the mouth of the uterus.

During a great part of the period of life of the foetus its urination is through the umbilicus. And this happens because the heel of the right [left] foot comes between the anus and the penis and shuts off the passage of all urine. Nature has provided for this by making a channel in the fundus of the bladder [urachus] through which urine goes from the bladder to the umbilicus and from the umbilical cord to the mouth of the uterus. Leonardo rendered this concept visually, and yet incorrectly, through a series of beautiful 3D drawings of a human fetus, where the heel of the baby shuts off the passage of the urine from the penis (Windsor, RL 19101r, RL 19102r, and RL 19103r).

Leonardo’s solution differed somewhat from that of his predecessors as well as his contemporaries, but it was no less ingenious and based on a mix of observation and reasoning. While it is evident that in his anatomical studies he was grappling with some of the most contested questions of generation and embryology of the period, he possessed the unique gift of being able to render these visually with an intensity and immediacy that remained unmatched for centuries. This example places Leonardo firmly in the context of his time, but does not deter present-day viewers from admiring Leonardo’s unique combination of anatomical knowledge, ingegno and draftsmanship.